Sunday, August 23, 2009

A Typical Week In The Life Of - Day 3

Today we're going to touch on layout and hydraulic calculations.

Prior to 1985 most hydraulic calculations were done by hand but today they are done by special computer programs that can do in a few minutes what used to take hours to do.

Below is a sketch of our 70'x100' building. Sprinkler heads are the red circles, pipe is red, walls are black.

Since this is an Ordinary Hazard Group II Occupancy we will use a design density of .20 gpm over the hydraulically most remote 1,500 sq. ft..

What a designer does is lay out a system he *thinks* will work based on past experience. You do this enough and in a few years you'll be able to guess and get it pretty close.

I don't think the layout I sketched will work, I think that second piece of 1" pipe from the end kills our chances, but we will try it anyway.

Click image to enlarge.

With sprinklers 12'-6" apart on lines and lines 10'-0" apart each sprinkler covers 125 sq. ft..

The number of sprinklers needing to be in the calculated area is 1,500/125=12. If heads were spaced 124 sq. ft. we would need 13 heads in the calculated area. We always round up to the nearest whole sprinkler.

Our hydraulic remote area has to be 1,500 sq. ft. and must be rectangular in shape with the long direction being at least 1.2 * sqrt of the area of application.

Rectangular length: 1.2*sqrt 1,500 or 46.47 feet. The long side of the rectangle must be parallel to the lines and you add sprinklers until the length is equal to or exceeds 46.47 feet.

The calculated area is located in the lower left corner of the building and is bounded by two walls and two green lines. The green numbers are "Nodes" or identifiers we will use in our hydraulic calculations.

The 12 heads we will calculate as open will be #1 through #4, #9 through #12 and #17 through #20. Sprinklers used will be Viking VK100 1/2" orifice brass upright sprinkler having a K-Factor equal to 5.6.

A K-Factor is a coefficient of discharge used to find the discharge of a sprinkler head at varying pressures. The formula is:

Q=K*P^.5 or Q=K*sqrtP

Where Q=Water in Gallons Per Minute, K=K-Factor and P is the Pressure at the sprinkler head in pounds per square inch or psi.

Sprinkler #1 covers an area of 125 sq. ft. and in order to provide a density of .20 per square foot over the area of sprinkler coverage it must discharge 25.0 gpm. 125*.20=25.0

Using Q=K*sqrt P we can determine the pressure required to discharge 25.0 gpm by:


In order to discharge 25.0 gpm a sprinkler with a K-Factor=5.6 must be supplied with 19.9 psi.

When hand calculating we will round our numbers to the nearest tenth.

When calculating sprinkler systems we proceed from the end sprinkler inwards. We will start with sprinkler head #1.

Ever connect two or three identical yard sprinklers together in series fed by a garden hose only to notice the sprinkler farthest away discharged the least water? When water travels through pipe it encounters pressure or friction loss.

In accordance with NFPA #13 Section this head loss loss is calculated using the Hazen-Williams formula shown to the right.

For wet pipe systems using black steel or galvanized pipe the friction loss coefficient or C-Value we use is 120.

For our purposes we will use schedule 40 black steel pipe that has the following inside pipe diameters:

1 1/4"=1.380"
1 1/2"=1.610"
2 1/2"=2.469"

For calculating friction loss the Engineering Toolbox has a little online calculator or you can do what I do and that's use a small scientific calculator similar to the Casio fx-115MS which I am using right now and can be purchased at K-Mart for around $20.00.

There is another way to calculate pressure loss in pipe besides using the
Engineering Toolbox and that is using Pipe Table B shown here.

On most wet pipe sprinkler systems C-120.

To calculate friction loss through 1 1/4" pipe Sch. 40 pipe while flowing 32.5 gpm use a scientific calculator for 32.5^1.85*1.34x10^-4

The answer is 0.084

Using the Engineering Toolbox how much head or friction loss will we encounter through the 1" pipe flowing from Node #1 to Node #2 while flowing 25.0 gpm?

I got a head loss of 0.197 psi per linear foot. For 12'-6" our total head loss between Node #1 and Node #2 will be 2.46 psi or we will call it 2.5 psi after rounding to nearest tenth.

What we are seeing is we require 19.9+2.5=22.4 psi pressure at Node #2 for us to be able to discharge 25.0 gpm at Node #1.

Now we have to add the flow of sprinkler Node #2 but we just can't add 25.0 gpm because we've already determined we must have 22.4 psi pressure at sprinkler Node #2.

How much water will be discharged from sprinkler Node #2 when supplied with 25.7 psi pressure?



q= 26.504 or 26.5 gpm after rounding.

Our minimum required flow from sprinkler Node #2 to sprinkler Node #3 is 25.0+26.5=51.5 gpm.

Remember, everything we do is backwards. With calculations we are moving from the farthest point on the system to the center which is the same way a system is drawn up or designed.

What is the head or friction loss with 51.5 gpm flowing through 1" pipe from sprinkler Node #2 to sprinkler Node #3?

I got 0.749 psi per linear foot or 12.5*0.749=9.4 psi for the 12'-6" length of 1" pipe.

At sprinkler Node #3 our system so far requires 35.7 psi (25.7+9.4=35.1 psi) at sprinkler Node #3 to adequately supply water to both sprinkler Node #1 and sprinkler Node #2 insuring each node discharges at least 25.0 gpm.

With 35.7 psi required at sprinkler Node #3 how much water will sprinkler Node #3 discharge?



q= 33.18 or 33.2 gpm after rounding.

Adding the 33.2 gpm to the required combined flow of 51.5 gpm the total water demand for sprinkler Node #1, #2 and #3 is 84.7 gpm.

Earlier was was talking about "theoretical minimum" water supply requirements mentioning it was always more in actual practice. For example a 1,500 square foot area with a minimum density of .20 gpm per sq. ft. with sprinklers spaced 125 sq. ft. would require 300.0 gpm but you can already see why it would be more. In what we've done with three heads, each requiring a minimum discharge of 25.0 gpm, we should only need 75.0 gpm but we require 84.7 gpm.

By this time you should be pretty well lost. It isn't something you master in a day, a week or even a year but once you've done it a while it does come easy.

It is more than most people realize and it isn't your normal everyday cad job.

We've only calculated three sprinkler heads and it's getting unwieldy. We do have a regular form we can use so let's go to that.

Saturday, August 22, 2009

A Typical Week In The Life Of - Day 2

Yesterday we conducted a flow test and obtained the following results:

Static Pressure: 54 psi
Residual Pressure: 48 psi
Rate of Flow: 1,113 gpm

An analysis of our water flow test is done using
N^1.85 graph paper.

Once plotted we can determine what water pressure will be available at any flow. For our project we can determine we will have approximately 52 psi available if your sprinkler produces a demand of 600 gpm. If we had a system that produced 1,400 gpm demand the city water supply would have 45 psi available.

The more water required the less pressure is available.

Yesterday we talked about how static pressure alone wasn't an indicator of the quality of an available water water supply.

Consider a few years ago I had a flow test that produced the following results:
Static Pressure: 115 psi Residual Pressure: 24 psi Pitot Pressure: 16 psi

(As you will see this supply sucks).

Using a coefficent of 0.90 what would be the calculated rate of flow if we obtained a pitot pressure of 16 psi?

d=Diameter in inches of discharge orifice
p=Pitot pressure in psi

Answer: 746*0.90=671 gallons per minute.

Static Pressure: 115 psi Residual Pressure: 24 psi
Rate of Discharge: 671 gallons per minute.

Plotting the test summary we obtain this graph:

By plotting two points on a curve (static pressure and residual pressure @ flow) we can determine what pressure will be available in the line at any flow.

When analyzing flow test results you want to keep in mind flow test results can vary hour by hour. The results you obtained today probably won't match the results you get tomorrow so when laying out a system make sure to leave yourself some "safety factor". I always attempt to give myself 10 psi.

Static pressure on a gravity flow municipality indicates the height of water level in the water tank. Water weighs 0.433 pounds per foot and we can use this to determine the height of water above our static pressure test gauge.

With a static pressure of 54 psi the water level is 54/.433=124.7 feet above the test gauge.

With a static pressure of 115 psi the water level is 115/.433=265.6 feet above the test gauge.

Caution is something you should always have.

Consider the water tower in the photo.

In large metropolitan areas the technician generally doesn't need to
be all that concerned because elevated tanks are generally much larger and there are multiple elevated tanks.

But in smaller towns and villages the techni
cian needs to be aware of not just the pressures available but the total water supply available as well.

From the two flow tests:

Test #1
Static Pressure: 54 psi
Residual Pressure: 48 psi
Rate of Flow: 1,113 gpm

Test #2
Static Pressure: 115 psi
Residual Pressure: 24 psi
Rate of Flow: 671 gpm

Which of the two flow test results do you suppose offers the "best" pressures as far as capable of producing the system with the smallest diameter pipes therefore the most economical system?

The answer is "it depends".

Let's superimpose the results of the second test on the graph with the first test.

The first thing we notice is that at 550 gpm 53 psi pressure is available at both tests.
We're going to concern ourselves with five occupancies as far as fire sprinklers are concerned.

Light Hazard Occupancies requires the least demanding fire sprinkler design. Light Hazard Occupancies include such occupancies as hospitals, nursing homes and office buildings. As can be determined from NFPA #13 the density for light hazard occupancies is .10 gpm over 1,500 sq. ft. with an additional 100 gpm for hose stream.

We can expect Light Hazard Occupancies to require not less than 150 gpm for sprinkler plus 100 gpm for hose allowance for a total water requirement of not less than 250 gpm.

Ordinary Hazard Group I Occupancies include those occupancies where storage does not exceed 8' in height and combustibility of product is low such as a light bulb factory or food processing plant.

The minimum density for an Ordinary Hazard Group I Occupancy is .15 gpm over 1,500 sq. ft. plus an additional 250 gpm for hose stream demand.

We can expect Ordinary Hazard Group I Occupancies to require not less than 225 gpm for sprinkler plus 250 gpm for hose allowance for a total water requirement of around 475 gpm.

Ordinary Hazard Group II Occupancies include those occupancies where storage does not exceed 12' in height and combustibility of product is moderate such as a shopping centers, drug stores, most furniture stores, shopping malls, machine shops and most factories.

The minimum density for an Ordinary Hazard Group II Occupancy is .20 gpm over 1,500 sq. ft. plus an additional 250 gpm for hose stream demand.

We can expect Ordinary Hazard Group II Occupancies to require not less than 300 gpm for sprinkler plus 250 gpm for hose allowance for a total water requirement of not less than 550 gpm.

Extra Hazard Group I Occupancies include those occupancies where storage does not exceed 12' in height and combustibility of product is greater such as die casting, metal extruding, plywood and particle board manufacturing. Printing (using inks having flash points below 100°F), rubber reclaiming, compounding, drying, milling, vulcanizing and saw mills.

The minimum density for an Extra Hazard Group I Occupancy is .30 gpm over 2,500 sq. ft. plus an additional 500 gpm for hose stream demand.

We can expect Extra Hazard Group I Occupancies to require not less than 750 gpm for sprinkler plus 500 gpm for hose allowance for a total water requirement of not less than 1,250 gpm.

And finally there are Extra Hazard Group II Occupancies which include those occupancies where storage does not exceed 12' in height and combustibility of product is high such as asphalt saturating, flammable liquids spraying, flow coating, manufactured home or modular building assemblies (where finished enclosure is present and has combustible interiors), open oil quenching, plastics processing, solvent cleaning, varnish and paint dipping.

The minimum density for an Extra Hazard Group I Occupancy is .40 gpm over 2,500 sq. ft. plus an additional 500 gpm for hose stream demand.

We can expect Extra Hazard Group II Occupancies to require not less than 1,000 gpm for sprinkler plus 500 gpm for hose allowance for a total water requirement of not less than 1,500 gpm.

You might be asking "What exactly is 'hose stream demand'?"

Sprinkler systems are designed to deliver a minimum quantity of water over the fire but what happens when the fire department rolls up, attaches hose lines to hydrants and starts spraying water on the fire?

They "rob water" from the overall system and hose stream allowances insures the system will continue to function as it should in spite of the disappearing water.

One can design most any sprinkler system given 20 to 30 psi but with these low pressures heads will have to be spaced closer together (more spinklers=more money) and pipes feeding sprinklers will have to be larger (bigger pipes=more money). While it is possible to design a system to work on 20 psi, assuming the building is not to high, the costs can get stupidly high.

The cost of running 4" pipe could run $4.00 per linear foot while the cost of running 8" pipe can easily exceed $30.00 per linar foot. Doesn't sound like much until you consider you could be easily dealing with a thousand feet of pipe. Lot of difference between $4,000 and $30,000.

Tomorrow we'll start hydraulic calculations so you can see this all start to go together.

A Typical Week In The Life Of - Day 1

It's Monday morning and we get a call from a developer 20 miles away who wants a price for having a sprinkler system installed at a new 7,000 sq. ft. drug store they are looking at building.

We don't know what the cost would be because pipe size is all dependent on the water pressure available. Larger pipe always costs more money not just in terms of material cost but labor to install as well. For example 6" pipe costs three times as much to purchase but can easily require twice the labor to install.

Before we can do anything we need to run a flow test.

Checking with the city we determine there's an 8" city water main running down the street in front of the proposed building and what we need now is two hydrants in front ideally "straddling" the property as shown above.

We're are going to conduct a flow test on "Hydrant A" using both "Hydrant A" and "Hydrant B".

The tools we need are a water pressure gauge with 2 1/2" NSHT (National Standard Hose Thread) adapter and a pitot tube which are shown in the photo to the right.

About the gauges. In my opinion the accuracy of the flow test we are about to conduct is the most important part of laying out any sprinkler system. We will want to use good quality gauges that have been lab certified for accuracy sometime in the preceding twelve months.

During my career I've made some mistakes; I've run into beams I didn't know were going to be there and I've missed heating ducts I didn't know were there and had to reroute pipe to go around obstacles but these mistakes are easily corrected in the field.
If you do this work you will make the same mistakes but these aren't really any big deal. Mistakes like this typically cost anywhere from a couple hundred to maybe even one or two thousand dollars but while nobody likes to lose money they'll happen.

The one mistake that has the potential to cost a lot of money, sometimes tens of thousands or even hundreds of thousands of dollars, is not using an accurate, up to date flow test in the design of your system. Being a certified layout technician carries a lot of responsibility and "missing it" is your mistake.

All the pipe sizes you use in designing your system will be based upon this flow test. If it is wrong your entire system is wrong and most likely a mistake like this will cost money to fix. Sometimes a lot of money.

You are also going to want a "Flow Test Summary" where you can document the flow test. I've included a copy of the flow test summary report I use to the left.

I do not carry a hydrant wrench, used to open and close hydrants, because if something breaks I don't want to be the one responsible. What I do is call either the water or fire department so they could have someone there to witness the results and operate the hydrants. If the hydrant breaks I want them to be the ones to break it.

Not to mention if you open a hydrant someone will notice and unauthorized operation of hydrants is against the law in all the municipalities I've done work in.

It is not good to spend an afternoon in jail.

After we get there the we'll connect the pressure gauge to our test hydrant, this is "Hydrant A", which is the upstream hydrant to obtain our static and residual pressures. Once connected we'll have someone from the fire department fully open the hydrant so we can obtain our static pressure.

The static pressure is going to look something like this... on this test we see a static pressure of 54 psi.
Static pressure is the pressure available in the line without water flowing. While most municipal water systems typically have from 50 to 80 psi available I've seen static pressures as low as 22 psi (almost always unusable) to as high as 240 psi as I found once in Akron, Ohio.

Now we need to flow "Hydrant B".

To flow the hydrant we'll have the water department remove the cap from the 2 1/2" hydrant opening then fully open the hydrant getting something like this.

I'm sure you've seen this before and now you know they're most likely conducting a flow test. Look for the guy holding a clipboard.

When the hydrant is fully open we're going to get two readings.

The first reading we'll get is the "residual pressure" or the pressure that is in the line with the downstream hydrant fully discharging.

On a gravity system, a gravity system is a system employing water storage tanks, the residual pressure will always be less than the static pressure.

With the hydrant fully open we expect to see a drop and we're right. Reading the gauge at "Hydrant A" we note the pressure has dropped 6 psi from 54 psi to 48 psi.

The residual pressure available for this flow test is 48 psi.

I've seen all kinds of residual pressure drops. I've seen those with static pressures of 60 psi drop to 58 or 59 psi and I've seen them drop from 60 psi to 12 psi.

You got to take your readings and you got to be accurate. Never guess

because if you guess it will come back to bite you.

I've always enjoyed conducting flow tests. They're different.

The last reading we need is the quantity of water being discharged from the open hydrant and we determine this by using the pitot tube to measure the force of water being expelled.

To obtain pitot pressure we place the opening in the center of the stream with the tip half of a diameter away from the hydrant butt. In the case of a 2 1/2" hydrant butt we would want to hold our tip 1 1/4" away from the opening as shown in the photo.

It's hard to see in this photo but our pitot pressure was 44 psi.

The formula for theoretical discharges through circular orifices is:


d=Diameter in inches of discharge orifice
p=Pitot pressure in psi

Commit this formula to memory because you will use it on every flow test you conduct.

The diameter of our outlet is 2.5 inches and our pitot pressure was 44 psi.

The theoretical discharge from the 2.5 inch hydrant butt with a pitot pressure of 44 psi is 1,237 gpm.

Wait, we're not done yet.

But the formula is for theoretical discharge from a perfect circular orifice and 2 1/2" open hydrant butts are not perfect. I guess this just goes to show nobody's butt is perfect. :)

We need to multiply the theoretical discharge by a coefficient of discharge which is recognized as 0.90 for relatively new hydrants which is most hydrants less than 60 years old.

1,237*0.90=1,113 gpm.

Looking at all that water coming out of the hydrant butt we viewing something real close to 1,113 gallons per minute.

Some insurance underwriters require a discharge coefficient of 0.80 so if this project was a Factory Mutual risk we would have to use a flow of 0.80*1,237=990 gpm.

For 90% of the projects you do you will be using a coefficient of 0.90.

So for our flow test we obtained the following results:

Static Pressure: 54 psi
Residual Pressure: 48 psi
Rate of Flow: 1,113 gpm

Using a coefficent of 0.90 what would be the calculated rate of flow if we obtained a pitot pressure of 20 psi?

Answer: 834*0.90=750 gallons per minute.

Using a coefficent of 0.90 what would be the calculated rate of flow if we obtained a pitot pressure of 40 psi? (It isn't double).

Answer: 1,179*0.90=1,061 gallons per minute.

Doubling the pressure does NOT double the discharge.

How accurate are the numbers? I wouldn't get all bunged up over a few gallons. 1,055 gpm is just as valid as 1,065 gpm but if truth be known it's probably within a few percentage points.

Professional Engineers, these are people with the initials PE after their names, are might cringe hearing me say this but we're getting awfully close to doing real engineering but it is important to recognize we are not engineers. We are highly specialized technicians.

Ok, now that's over and we'll talk a bit about what we did during the ride back to the office. It's getting close to lunch time and I'll buy, you listen.

Static pressure by itself doesn't mean anything to us. If you told me the line in front of a building had 140 psi of pressure I couldn't tell you for certain if that would be adequate to supply a fire sprinkler any more than if you told me the line had 45 psi of pressure. You can't tell from this one number.

I got an idea 140 psi would be a great water supply but I wouldn't stake my life and reputation on it until I conducted a flow test. While the guess might be good there's to much money and liability attached to go around foolishly guessing.

Sprinkler systems are designed using the "density area" method. The density for a shopping mall, grocery or drug store is .20 gpm over the most remote 1,500 sq. ft. plus 250 gpm for hose stream. Using the density area method the theoretical minimum amount of water a sprinkler system would have to have would be .20*1,500=300 gpm for sprinklers plus an additional 250 gpm for fire department use for a total of 550 gpm. This is the theoretical minimum and I can tell you now it will be more, probably 10% to 20% more, but it can not be less than 550 gpm.

What the density area means is we have to be able to prove the sprinkler system we install is capable of discharging a minimum of .20 gpm per square foot over an area of 1,500 square feet. We are not interested in what it will actually do but what we must show is it will do at least the minimum... anything over is just gravy.

This brings up an interesting point, does the size of the building have anything to do with the total amount of water required?

The answer is no.

Here's the deal, 99% of sprinklers don't go off like you see in the movies, each individual sprinkler head is individually activated by heat. Figure one shows a Viking VK100 1/2" standard response sprinker rated at 200 Deg. F. The green liquid in the bulb indicates temperature rating.

On the vast majorit of systems pipe connected to the sprinkler is full of water under pressure all ready to go. The only thing stopping water from being discharged is the glass bulb that holds the sprinkler seat (seal) in place. Once this glass bulb breaks water will flow instantly.

Sprinkler heads can easily be activated by holding a heat source to the glass bulb. In Fig. 2 I am going to break the glass bulb by applying heat from a common cigarette lighter.

It doesn't take much, it happens fast and if connected to a sprinkler system water is instant. Lots and lots of water, it isn't like the movies.

In just a few short seconds the liquid in the bulb expands breaking the bulb which releases the seat allowing water to flow.

Sprinkler heads are a one time operation deal. Once they operate you have to replace.

Ever wonder how much water one will put out? That depends on the water pressure.



k=discharge constant
p=pressure in psi
q=gallons per minute.

In the case of the VK100 1/2" sprinkler the k=factor=5.6.

If a sprinkler is supplied with 100 psi it will discharge 5.6*100^.5 or 56.o gallons per minute. 56.0 gpm is a lot of water and to put it into perspective it will fill a 55 gallon drum in less than a minute.

If supplied with 50 psi the 1/2" VK100 sprinkler will discharge 5.6*50^.5 or 39.6 gallons per minute. Just because you double the pressure does not mean you double the discharge.

People often ask about high challenge fires, will sprinklers put out a plastics fire or a pile of styrofoam cups 20 feet high?

Yes, they will if properly designed. We have heads with k-factors of 25.0 with a maximum allowable spacing of 100 sq. ft. per sprinkler. You find these kinds of sprinklers in warehouses where you have high challenge fires such as foam rubber warehouses.

With something like a foam rubber mattress you will most likely have a large fire pump capable of pumping 2,000 to 3,000 gallons per minute at 125 psi.

From a single open k-25 sprinkler head:

q=25.0*125^.5 or 279 gpm from one sprinkler head. This sprinkler will fill a 55 gallon drum in under 12 seconds. That's a lot of water.

Imagine the amount of water if you had 12 of these sprinklers going off.

You put any fire under Niagra Falls and it will go out.

Sorry, kind of got sidetracked there.

With the 1,500 sq. ft. area of operation the idea is to either control or extinguish the fire before it grows out of that area.

If the entire building is on fire what's there to save?

A small 1,500 sq. ft. building will require a minimum of 550 gallons per minute.

A large one million square foot building will require the same amount of water.... 550 gallons per minute. In each case the area of operation is the same.

While 550 is the theoretical minimum it will be more... probably 600 gpm or somewhere around there.

When flowing water through a pipe the more water you flow the less pressure you have available. We saw that in our flow test; without water flowing we had 54 psi available but with 1,113 gpm flowing we had only 48 psi.

The reason we did this flow test was to determine how much pressure we have available to design our system to at 600 gpm or whatever our end demand will be.

Enough for one day. We'll talk about flow test evaluation tomorrow.

And here you thought high school algebra was a waste of time.

Thursday, August 20, 2009

What kind of skills do you need to start?

Layout technicians spend most, I am guessing 75%-90% on average, of their time in front of a computer screen "building" systems using AutoCad but in my opinion AutoCad skills are a small part of the skills required for the job.

High school graduate is a must.

Must have math skills equal to at least high school algebra I and geometry certainly doesn't hurt.

In my opinion reading and interpretation skills will have to be better than average. We're a heavily regulated industry and just the NFPA #13 Handbook has 1,200 pages full of definitions like Section 5.4.1 having to do with Hazard Classifications.

5.4.1* Extra Hazard (Group 1). Extra hazard (Group 1) occupancies shall be defined as occupancies or portions of other occupancies where the quantity and combustibility of contents are very high and dust, lint, or other materials are present, introducing the probability of rapidly developing fires with high rates of heat release but with little or no combustible or flammable liquids.
5.4.2* Extra Hazard (Group 2). Extra hazard (Group 2) occupancies shall be defined as occupancies or portions of other occupancies with moderate to substantial amounts of flammable or combustible liquids or occupancies where shielding of combustibles is extensive.
5.5* Special Occupancy Hazards.
5.6* Commodity Classification.
See Section C.2.
5.6.1 General.* Classification of Commodities. Commodity classification and the corresponding protection requirements shall be determined based on the makeup of individual storage units (i.e., unit load, pallet load). When specific test data of commodity classification by a nationally recognized testing agency are available, the data shall be permitted to be used in determining classification of commodities. Mixed Commodities. Protection requirements shall not be based on the overall commodity mix in a fire area. Unless the requirements of or are met, mixed commodity storage shall be protected by the requirements for the highest classified commodity and storage arrangement. The protection requirements for the lower commodity class shall be permitted to be utilized where all of the following are met:
(1) Up to 10 pallet loads of a higher hazard commodity, as described in 5.6.3 and 5.6.4, shall be permitted to be present in an area not exceeding 40,000 ft2 (3716 m2).
(2) The higher hazard commodity shall be randomly dispersed with no adjacent loads in any direction (including diagonally).
(3) Where the ceiling protection is based on Class I or Class II commodities, the allowable number of pallet loads for Class IV or Group A plastics shall be reduced to five. Mixed Commodity Segregation. The protection requirements for the lower commodity class shall be permitted to be utilized in the area of lower commodity class, where the higher hazard material is confined to a designated area and the area is protected to the higher hazard in accordance with the requirements of this standard.
5.6.2 Pallet Types. When loads are palletized, the use of wooden or metal pallets shall be assumed in the classification of commodities. For Class I through Class IV, when unreinforced polypropylene or high-density polyethylene plastic pallets are used, the classification of the commodity unit shall be increased one class (e.g., Class III will become Class IV and Class IV will become cartoned unexpanded Group A plastics).
Protection requirements are found throughout the standards and below I've included a snapshot dealing with the protection of idle wood pallets using control mode sprinklers.

This represents just one page out of the 1,200 or more contained in the handbook.

It isn't the worlds easiest reading and you're not going to breeze through it in an evening.

It also needs to be recognized in addition to the NFPA #13 Handbook we commonly deal with NFPA #14 having to do with standpipes, NFPA #15 having to do with water spray systems, NFPA #20 having to do with fire pumps, NFPA #24 having to do with underground fire line and hydrant requirements and then there is NFPA #25 having to do with inspections and testing.

On top of the NFPA standards there are building codes that you would need to be familiar with, at least those sections having to do with fire protection, and then there are a number of insurance company standards.

In addition to the standards there's manufacture's literature that a technician is going to have to read and fully understand.

There are literally thousands of different kinds of sprinkler heads and nozzles available on the market.

For an idea of the number and complexity visit Viking Corporation.

I would have to say reading skills and comprehension rank right up there.

Thursday, August 13, 2009

There's more to it than overhead pipes

Of course there are site drawings, these appear to be similar to civil engineering drawings, but what happens if you're in the country without public water?

You can get creative with a water storage tank or (my personal favorite) laying out a vertical turbine fire pump taking suction from a pond, lake or even a well if water is available. For wells there usually isn't enough .

When designing something like this the designer has to work with a professional engineer because some things I can do and some I can't.

I can determine the size and depth of the pond needed, the size of the pumphouse, all the piping, size and layout of required screens, trash bars and water intake way.

But what I can'd do is engineer the concrete and I leave that up to the professional engineer.

The job on the drawing is a recently completed 1,500 gpm @ 120 psi 125 HP electrically driven vertical turbine fire pump. What I do is create what I want and then give a copy to the professional engineer who will detail the actual structure with rebar, mesh and calculate the loadings that are required.

Fire pumps come in all different sizes. You can get a vertical turbine as small as 250 gpm or as large as 5,000 gpm. They can be electric or diesel engine driven.

I'm just pointing out there is a lot more to this job than someone might at first think.

Sunday, August 9, 2009

How tough are NICET tests?

For most of it not all that bad really and for both layout and inspections there are a number of elements a complete novice can pass.

The Automatic Sprinkler System Layout PROGRAM DETAIL MANUAL requires passage of a minimum of 50 elements and depending on your abilities 2, 3 or 4 of the 50 required elements might require serious study or even tutoring.

There's a large number of NICET II certificate holders that can't get Level III certification just because they can't pass one or two elements. One of the stumbling blocks is the "advanced hydraulic calculations" element.

The Advanced Hydraulic Calculations is a Level III "core element" which means Level III certification will not be issued until this element is passed. It doesn't matter, you can pass every other single element NICET offers but until you pass this Level III will not be awarded. That's the way NICET works.

I was lucky I found this element easy enough because I started hydraulic calculations in the mid 1970's, before personal computers, when we were doing them by hand. Today our computers do the calculations for us, what used to take an hour or two or three now takes five seconds, which leaves someone new somewhat vulnerable. You are going to have to learn how to do this.

Understand thoroughly advanced hydraulic calculations as applied to looped and gridded systems, velocity pressures, etc. Perform Hardy-Cross analysis of flow in a simple looped system. (NFPA 13, Layout, Detail and Calculation of Fire Sprinkler Systems)
Click on the image to view a typical advanced hydraulic calculation problem. This is not easy for most of us.

If you aren't used to doing it I don't think you will be finding it easy.

Another element that stops people, especially those who last did an algebra or trigonometric problem 22 years ago in high school, is "Intermediate Mathematics".

Perform mathematical calculations utilizing basic algebra (fundamental laws, algebraic expressions), geometry, and the trigonometric functions of right triangles. (See basic textbooks on algebra and trigonometry)

This is a Level I core element and until this is passed NICET will not issue any certification.

I would also take exception to the description "trigonometric functions of right triangles". Unless it has been changed over the last few years the trinonometric questions I had involved triangles but they were not right triangles.

I had to take the test three times to obtain Level III certification and a fourth time to obtain Level IV certification. This is pretty well average because you are limited to the number of elements you can take in a single sitting.

For example you are required to have 50 elements for Level III but the maximum number of elements you can take in one sitting is 34. If you miss just one core element you'll end up waiting six months before you take it again.

The first three times I took the exam I seem to remember we started at 8:30 AM, broke for lunch for exactly one hour and finshed up around 3:30 or 4:00 PM. The fourth time I took the exam, this was getting the rest of elements I needed for Level IV, I had most passed and was out of the classroom by noon.

The tests are open book but they are timed. If you have to look more than one or two questions you will run out of time and won't pass anyway.

Computers and programmable calculators are not allowed.

Government issued photo ID required.

During lunch break people are clustered about the hallway, these tests are given mostly at community colleges by a proctor, furiously looking up answers to questions they remembered. Once your open book material is cleared for use in the classroom it can not be removed until the test is done. For this reason it is wise to have two sets of source material.

And that's the testing procedure, have fun!

Saturday, August 8, 2009

If "Layout" Doesn't Sound Like Your Cup Of Tea What About Inspections?

Up to this time I've been talking about Automatic Sprinkler System Layout but there's also Inspection and Testing of Water-Based Systems that you might interest you.

This certification program was designed for engineering technicians in the automatic fire sprinkler industry who are engaged in the physical and mechanical aspects of inspection, testing, and maintenance of water-based systems including foam and foam-water systems. (The program does not cover systems that deal with CO2, halon, and dry chemical.)
Inspection and Testing of Water-Based Systems comprises three levels of certification. Level I was designed for technicians who assist in the inspection and/or testing of fire protection systems, Level II is for those who perform standardized tasks under routine conditions as assigned, and Level III is for those who perform comprehensive inspections of complex systems without supervision. Certification at Levels II and III does not require prior certification at Level I. Certification at Levels II and III does not require prior certification at the lower level, but it does require meeting the certification requirements of the lower levels.
This sub-field is relatively new having only been around for 10 years and is fast becoming one of the most sought after technicians there are.

Using Google to search "nicet sprinkler inspector" brings up 50,400 pages of mostly jobs that are going begging. Right now certified inspectors are in even more demand than certified layout technicians. It is really amazing how much demand there is.

How much? I have little doubt if someone could magically drop of thirty NICET III certified inspectors at the bus Atlanta bus station with $500 in their pocket, a rental car and access to the internet they would all have jobs by the end of the week.

Like the layout technicians certified inspectors are even harder to find.

As of April, 2009 the Georgia has a total of 84 NICET III inspectors living in the state.


Enclose a non-refundable fifty dollar $50.00 application fee and an a non-refundable fifty dollars $50.00 filing fee in the form of a company check or money order made payable to the State Fire Marshal’s Office (personal checks are not accepted). In addition, provide a resume of your work experience, including dates directly related to the inspection of fire protection sprinkler systems. Furthermore, state your knowledge and experience of the inspection process. Include any education and /or certifications i.e. N.I.C.E.T III certification in Inspections & Testing of Sprinkler Systems which is directly related to the inspection & testing of fire protection sprinkler systems. Submit this information on an attached, but separate sheet of paper, along with this application. Include a copy of your current Inspectors License and a copy of your N.I.C.E.T test level met letter (REQUIRED) or N.I.C.E.T inspection and testing certification. In compliance with O.C.G.A. Chapter 25-11, I hereby request I be issued a Sprinkler Systems Inspector License or have my Inspector License renewed by the Georgia Safety Fire Commissioner. I intend to engage in one or all of the following: The inspection and testing of water based fire protection systems.
In Georgia sprinkler systems are required be be inspected, tested and tagged annually but before we research demand let's take a look at what a day in the life of a typical certified inspector might be like.

Having called the day before our inspector gets on the road at 7:00 AM to get to his first appointment shortly after 8:00 AM. This inspection is rather simple, a single wet pipe spinkler system it takes a little over an hour and a half to walk through the building doing a visual inspection, testing the alarms, opening and closing valves (the most physically challenging part of the job), performing a main drain test and filling out the required paperwork.

At 10:15 AM our intrepid inspector is at his second appointment of the day which is a small manufacturing plant having one wet system and two dry systems. Having worked through lunch it's 1:15 PM by the time he's completed all his required tasks.

Grabbing a quick bite to eat on the road our inspector is at this third appointment of the day by 2:00 PM it's just a single small wet pipe system and he's out of there by 3:15 PM and at his final appointment of the day at 4:00 PM which is a motel.

The motel is completed by 5:30 PM, all the paperwork is completed and our inspector finally heads for home arriving at 6:30 PM. It's been a long day but not unusual.

This represents an "average day" and our inspector inspected six systems. In my opinion this is more than "average" with the "average" number of inspections a day being closer to four (my opinion) but we'll leave it at six.

Let's do the math.

A conservative estimate of the number of sprinkler systems in Georgia would be 500,000. I actually think it is but we'll leave it at 500,000.

If each inspector did six inspections per day for 250 days an inspector would perform 1,500 inspections annually. Bear in mind I think the 1,500 inspections figure is high with reality being closer to 1,000 to 1,200.

With 83 inspectors each doing 1,500 inspections a year the maximum possible number of inspections that can be performed in a year is 124,500 or not even a fourth of what is required.

As dire as this picture is it's even worse because I serously doubt an inspector would be able to average 6 inspections per day for 250 days. The actually figure would be closer to 4 or 5.

Then, on top of all this, the insurance carriers of many large industrial plants require quarterly and not just annual inspections.

The point I am making is the industry is woefully short of qualified inspectors and it is only going to get worse as more states adopt laws requiring inspections.

Some states, such as Texas and Florida, only require a NICET II to obtain a license to perform inspections while others, like Georgia, require a NICET III.

Personally I think NICET II with two years is not enough experience but those decisions aren't up to me.

How many new inspectors are being added?

Not many.

The push for NICET III inspectors has been going on for about six years and in that time the number of Level III inspectors went from a literally handful to 83. That's an average of just 13.8 per year or a little over 1 per month.

But the big growth spurt has slowed considerably because many who had the required experience already have the certificate.... there are fewer coming up behind the ones that blazed the trail.

But I will know for certain the November 3rd when I purchased an updated registry. We know there were 83 on April 3rd and we'll compare that with the new numbers in November.

Getting certified.

A number of current inspectors came from the ranks of experienced sprinkler fitters (the guys who actually do the installation) but that's the hard way to get there in my opinion.

Because of prohibitive training costs you can forget being hired on as a trainee, for between two to five years depending on state licensing requirements, before you can be productive in bringing income to the company.

Once again the easiest route will be a technical school.

Bates College in Olympia, Washington offers an AS degree in inspections and I am pretty sure there's a few more but will leave the searching up to you.


Pay varies around the country but from what I have seen it appears to be between $18 and $22 an hour but almost all include some sort of performance commission of between 8% and 12% of sales. If the average inspection sells for $150.00 and an inspector does 5 per day total sales equals $750.00. 10% of $750.00 equals $75.00 which is added to the hourly wage. With these schemes it is not unusual for inspectors to receive $300.00 to $500.00 added to their weekly pay in bonuses or commissions.

I've known a number of inspectors to make in excess of $60,000.00.

Many states accept NICET II for inspections and I suspect pay in the states that do accept Level II would be a little less. Nothing to base this on just my gut feeling.

There's lots of road miles that come with this job with working in a rural area 100 or more miles a day being normal. Nearly all inspectors I know have company vehicles furnished.

A clean driving record is an absolute must for a job like this.